Noble gases facts, information, pictures | Encyclopedia.com articles about Noble gases Isolation of the Noble Gases HELIUM. Helium is an unusual element in many respects—not least because it is the only element to have first been identified in the Solar System before it was discovered on Earth. This is significant, because the elements on Earth are the same as those found in space: thus, it is more than just an attempt at sounding poetic when scientists say that humans, as well as the world around them, are made from "the stuff of stars." In 1868, a French astronomer named Pierre Janssen (1824-1907) was in India to observe a total solar eclipse. To aid him in his observations, he used a spectroscope, an instrument for analyzing the spectrum of light emitted by an object. What Janssen's spectroscope showed was surprising: a yellow line in the spectrum, never seen before, which seemed to indicate the presence of a previously undiscovered element. Janssen called it "helium" after the Greek god Helios, or Apollo, whom the ancients associated with the Sun .

Janssen shared his findings with English astronomer Sir Joseph Lockyer (1836-1920), who had a worldwide reputation for his work in analyzing light waves. Lockyer, too, believed that what Janssen had seen was a new element, and a few months later, he observed the same unusual spectral lines. At that time, the spectroscope was still a new invention, and many members of the worldwide scientific community doubted its usefulness, and therefore, in spite of Lockyer's reputation, they questioned the existence of this "new" element. Yet during their lifetimes, Janssen and Lockyer were proven correct. NEON, ARGON, KRYPTON, AND XENON. They had to wait a quarter century, however. In 1893, English chemist Sir William Ramsay (1852-1916) became intrigued by the presence of a mysterious gas bubble left over when nitrogen from the atmosphere was combined with oxygen. This was a phenomenon that had also been noted by English physicist Henry Cavendish (1731-1810) more than a century before, but Cavendish could offer no explanation.

Ramsay, on the other hand, had the benefit of observations made by English physicist John William Strutt, Lord Rayleigh (1842-1919). Up to that time, scientists believed that air consisted only of oxygen, carbon dioxide, and water vapor. However, Rayleigh had noticed that when nitrogen was extracted from air after a process of removing those other components, it had a slightly higher density than nitrogen prepared from a chemical reaction. In light of his own observations, Ramsay concluded that whereas nitrogen obtained from chemical reactions was pure, the nitrogen extracted from air contained trace amounts of an unknown gas. Ramsay was wrong in only one respect: hidden with the nitrogen was not one gas, but five. In order to isolate these gases, Ramsay and Rayleigh subjected air to a combination of high pressure and low temperature, allowing the various gases to boil off at different temperatures. One of the gases was helium—the first confirmation that the element existed on Earth—but the other four gases were previously unknown. The Greek roots of the names given to the four gases reflected scientists' wonder at discovering these hard-to-find elements: neos (new), argos (in active), kryptos (hidden), and xenon (stranger).

RADON. Inspired by the studies of Polish-French physicist and chemist Marie Curie (1867-1934) regarding the element radium and the phenomenon of radioactivity (she discovered the element, and coined the latter term), German physicist Friedrich Dorn (1848-1916) became fascinated with radium. Studying the element, he discovered that it emitted a radioactive gas, which he dubbed "radium emanation." Eventually, however, he realized that what was being produced was a new element. This was the first clear proof that one element could become another through the process of radioactive decay. Ramsay, who along with Rayleigh had received the Nobel Prize in 1904 for his work on the noble gases, was able to map the new element's spectral lines and determine its density and atomic mass. A few years later, in 1918, another scientist named C. Schmidt gave it the name "radon." Due to its behavior and the configuration of its electrons, chemists classified radon among what they continued to call the "inert gases" for another half-century—until Bartlett's preparation of xenon compounds in 1962.

Presence of the Rare Gases on Earth IN THE ATMOSPHERE. Though the rare gases are found in minerals and meteorites on Earth, their greatest presence is in the planet's atmosphere. It is believed that they were released into the air long ago as a by-product of decay on the part of radioactive materials in the Earth's crust. Within the atmosphere, argon is the most "abundant"—in comparative terms, given the fact that the "rare gases" are, by definition, rare. Nitrogen makes up about 78% of Earth's atmosphere and oxygen 21%, meaning that these two elements constitute fully 99% of the air above the Earth. Argon ranks a distant third, with 0.93%. The remaining 0.07% is made up on water vapor, carbon dioxide, ozone (O3), and traces of the noble gases. These are present in such small quantities that the figures for them are not typically presented as percentages, but rather in terms of parts per million (ppm). The concentrations of neon, helium, krypton, and xenon in the atmosphere are 18, 5, 1, and 0.09 ppm respectively. IN THE SOIL.

Radon in the atmosphere is virtually negligible, which is a fortunate thing, in light of its radioactive qualities. Few Americans, in fact, even knew of its existence until 1988, when the United States Environmental Protection Agency (EPA) released a report estimating that some ten million American homes had potentially harmful radon levels. This set off a scare, and during the late 1980s and 1990s, sales of home radon detectors boomed. Meanwhile, the federal government increased concerns with additional reports, advising people to seal their basements and ventilate their homes if radon exceeded certain levels. A number of scientists have disputed the government's claims, yet some regions of the United States appear to be at relatively high risk due to the presence of radon in the soil. The element seems to be most plentiful in soils containing high concentrations of uranium. If radon is present in a home that has been weather-sealed to improve the efficiency of heating and cooling systems, it is indeed potentially dangerous to the residents. Chinese scientists in the 1960s made an interesting discovery regarding radon and its application to seismography, or the area of the earth sciences devoted to studying and predicting earthquakes.

Radon levels in groundwater, the Chinese reports showed, rise considerably just before an earthquake. Since then, the Chinese have monitored radon concentrations in water, and used this data to predict earthquakes. EXTRACTING RARE GASES. Radon, in fact, is not the only rare gas that can be obtained as the result of radioactive decay: in 1903, Ramsay and British chemist Frederick Soddy (1877-1956) showed that the breakdown of either uranium or radium results in the production of helium atoms (beta particles). A few years later, English physicist Ernest Rutherford (1871-1937) demonstrated that radiation carrying a positive electrical charge (alpha rays) was actually a stream of helium atoms stripped of an electron. Many of the noble gases are extracted by liquefying air—that is, by reducing it to temperatures at which it assumes the properties of a liquid rather than a gas. By controlling temperatures in the liquefied air, it is possible to reach the boiling point for a particular noble gas and thereby extract it, much as was done when these gases were first isolated in the 1890s. THE UNIQUE SITUATION OF HELIUM.

Helium is remarkable, in that it only liquefies at a temperature of −457.6°F (−272°C), just above absolute zero. Absolute zero is the temperature at which the motion of atoms or molecules comes to a virtual stop, but the motion of helium atoms never completely ceases. In order to liquefy it, in fact, even at those low temperatures, it must be subjected to pressures many times that exerted by Earth's atmosphere. Given these facts, it is difficult to extract helium from air. More often, it is obtained from natural gas wells, where it is present in relatively large concentrations—between 1% and 7% of the natural gas. The majority of the Earth's helium supply belongs to the United States, where the greatest abundance of helium-supplying wells are in Texas , Oklahoma , and Kansas . During World War II , the United States took advantage of this supply of relatively inexpensive helium to provide buoyancy for a fleet of airships used for reconnaissance. There is one place with an abundant supply of helium, but there are no plans for a mining expedition any time soon. That place is the Sun, where the nuclear fusion of hydrogen atoms creates helium.

Indeed, helium seems to be the most plentiful element of all, after hydrogen, constituting 23% of the total mass of the universe. Why, then, is it so difficult to obtain on Earth? Most likely because it is so light in comparison to air; it simply floats off into space. Applications for the Noble Gases RADON, ARGON, KRYPTON, AND XENON. Though radon is known primarily for the hazards it poses to human life and well-being, it has useful applications. As noted above, its presence in groundwater appears to provide a possible means of predicting earthquakes. In addition, it is used for detecting leaks, measuring flow rates, and inspecting metal welds. One interesting use of argon and, in particular, the stable isotope argon-40, is in dating techniques used by geologists, paleontologists, and other scientists studying the distant past. When volcanic rocks are subjected to extremely high temperatures, they release argon, and as the rocks cool, argon-40 accumulates.

Because argon-40 is formed by the radioactive decay of a potassium isotope, potassium-40, the amount of argon-40 that forms is proportional to the rate of decay for potassium-40. The latter has a half-life of 1.3 billion years, meaning that it takes 1.3 billion years for half the potassium-40 originally present to be converted to argon-40. Using argon-40, paleontologists have been able to estimate the age of volcanic layers above and below fossil and artifact remains in east Africa. Krypton has a number of specialized applications—for instance, it is mixed with argon and used in the manufacture of windows with a high level of thermal efficiency. Used in lasers, it is often mixed with a halogen such as fluorine. In addition, it is also sometimes used in halogen sealed-beam headlights. Many fans of Superman, no doubt, were disappointed at some point in their lives to discover that there is no such thing as "kryptonite," the fictional element that caused the Man of Steel to lose his legendary strength. Yet krypton—the real thing—has applications that are literally out of this world.

In the development of fuel for space exploration, krypton is in competition with its sister element, xenon. Xenon offers better performance, but costs about ten times more to produce; thus krypton has become more attractive as a fuel for space flight. In addition to its potential as a space fuel, xenon is used in arc lamps for motion-picture film projection, in high-pressure ultraviolet radiation lamps, and in specialized flashbulbs used by photographers. One particular isotope of xenon is utilized for tracing the movement of sands along a coastline. Xenon is also applied in high-energy physics for detecting nuclear radiation in bubble chambers. Furthermore, neuroscientists are experimenting with the use of xenon in diagnostic procedures to clarify x-ray images of the human brain. NEON. Neon, of course, is best-known for its application in neon signs, which produce an eye-catching glow when lit up at night. French chemist Georges Claude (1870-1960), intrigued by Ramsay's discovery of neon, conducted experiments that led to the development of the neon light in 1910. That first neon light was simply a glass tube filled with neon gas, which glowed a bright red when charged with electricity.

Claude eventually discovered that mixing other gases with neon produced different colors of light. He also experimented with variations in the shapes of glass tubes to create letters and pictures. By the 1920s, neon light had come into vogue, and it is still popular today. Modern neon lamps are typically made of plastic rather than glass, and the range of colors is much greater than in Claude's day: not only the gas filling, but the coating inside the tube, is varied, resulting in a variety of colors from across the spectrum. Though the neon sign is its best-known application, neon is used for many other things. Neon glow lamps are often used to indicate on/off settings on electronic instrument panels, and lightweight neon lamps are found on machines ranging from computers to voltage regulators. In fact, the first practical color television, produced in 1928, used a neon tube to produce the red color in the receiver. Green came from mercury, but the blue light in that early color TV came from another noble gas, helium. HELIUM. Helium, of course, is widely known for its use in balloons—both for large airships and for the balloons that have provided joy and fun to many a small child.

Though helium is much more expensive than hydrogen as a means of providing buoyancy to airships, hydrogen is extremely flammable, and after the infamous explosion of the airship Hindenburg in 1937, helium became the preferred medium for airships. As noted earlier, the United States military made extensive use of helium-filled airships during the World War II. The use of helium for buoyancy is one of the most prominent applications of this noble gas, but far from the only one. In fact, not only have people used helium to go up in balloons, but divers use helium for going down beneath the surface of the ocean. In that situation, of course, helium is not used for providing buoyancy, but as a means of protecting against the diving-related condition known as "the bends," which occurs when nitrogen in the blood bubbles as the diver rises to the surface. Helium is mixed with oxygen in diver's air tanks because it does not dissolve in the blood as easily as nitrogen. Among the most fascinating applications of helium relate to its extraordinarily low freezing point.

Helium has played a significant role in the low-temperature science known as cryogenics, and has found application in research concerning superconductivity: the use of very low temperatures to develop materials that conduct electrical power with vastly greater efficiency than ordinary conductors. Close to absolute zero, helium transforms into a highly unusual liquid unlike any known substance, in that it has no measurable resistance to flow. This means that it could carry an electrical current hundreds of times more efficiently than a copper wire. WHERE TO LEARN MORE "The Chemistry of the Rare Gases" (Web site). < (May 13, 2001). "Homework: Science: Chemistry: Gases" Channelone.com (Web site). < (May 12, 2001). Knapp, Brian J.; David Woodroffe; David A. Hardy. Elements. Danbury, CT: Grolier Educational, 2000. Mebane, Robert C. and Thomas R. Rybolt. Air and Other Gases. Illustrations by Anni Matsick. New York : Twenty-First Century Books, 1995. "Noble Gases" Xrefer.com (Web site).

< (May 13, 2001). Rare Gases. Praxair (Web site). < (May 13, 2001). Stwertka, Albert. Superconductors: The Irresistible Future. New York: F. Watts, 1991. Taylor, Ron. Facts on Radon and Asbestos. Illustrated by Ian Moores. New York: F. Watts, 1990. Cite this article Pick a style below, and copy the text for your bibliography. MLA noble gas | Definition, Properties, Uses, & Facts | Britannica.com neon (Ne) Noble gas, any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table . The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og). The noble gases are colourless, odourless, tasteless, nonflammable gases .

They traditionally have been labeled Group 0 in the periodic table because for decades after their discovery it was believed that they could not bond to other atoms ; that is, that their atoms could not combine with those of other elements to form chemical compounds . Their electronic structures and the finding that some of them do indeed form compounds has led to the more appropriate designation , Group 18. When the members of the group were discovered and identified, they were thought to be exceedingly rare, as well as chemically inert, and therefore were called the rare or inert gases. It is now known, however, that several of these elements are quite abundant on Earth and in the rest of the universe , so the designation rare is misleading. Similarly, use of the term inert has the drawback that it connotes chemical passivity, suggesting that compounds of Group 18 cannot be formed. In chemistry and alchemy , the word noble has long signified the reluctance of metals , such as gold and platinum , to undergo chemical reaction ; it applies in the same sense to the group of gases covered here. The abundances of the noble gases decrease as their atomic numbers increase. Helium is the most plentiful element in the universe except hydrogen .

All the noble gases are present in Earth’s atmosphere and, except for helium and radon, their major commercial source is the air , from which they are obtained by liquefaction and fractional distillation . Most helium is produced commercially from certain natural gas wells. Radon usually is isolated as a product of the radioactive decomposition of radium compounds. The nuclei of radium atoms spontaneously decay by emitting energy and particles, helium nuclei ( alpha particles ) and radon atoms. Some properties of the noble gases helium polonium (Po) In 1785 Henry Cavendish , an English chemist and physicist, found that air contains a small proportion (slightly less than 1 percent) of a substance that is chemically less active than nitrogen . A century later Lord Rayleigh , an English physicist, isolated from the air a gas that he thought was pure nitrogen, but he found that it was denser than nitrogen that had been prepared by liberating it from its compounds. He reasoned that his aerial nitrogen must contain a small amount of a denser gas. In 1894, Sir William Ramsay , a Scottish chemist, collaborated with Rayleigh in isolating this gas, which proved to be a new element— argon .

Apparatus used in the isolation of argon by English physicist Lord Rayleigh and chemist Sir William … Encyclopædia Britannica, Inc. After the discovery of argon, and at the instigation of other scientists, in 1895 Ramsay investigated the gas released upon heating the mineral clevite, which was thought to be a source of argon. Instead, the gas was helium , which in 1868 had been detected spectroscopically in the Sun but had not been found on Earth . Ramsay and his coworkers searched for related gases and by fractional distillation of liquid air discovered krypton , neon , and xenon , all in 1898. Radon was first identified in 1900 by German chemist Friedrich E. Dorn; it was established as a member of the noble-gas group in 1904. Rayleigh and Ramsay won Nobel Prizes in 1904 for their work.

In 1895 the French chemist Henri Moissan , who discovered elemental fluorine in 1886 and was awarded a Nobel Prize in 1906 for that discovery, failed in an attempt to bring about a reaction between fluorine and argon. This result was significant because fluorine is the most reactive element in the periodic table. In fact, all late 19th- and early 20th-century efforts to prepare chemical compounds of argon failed. The lack of chemical reactivity implied by these failures was of significance in the development of theories of atomic structure. In 1913 the Danish physicist Niels Bohr proposed that the electrons in atoms are arranged in successive shells having characteristic energies and capacities and that the capacities of the shells for electrons determine the numbers of elements in the rows of the periodic table. On the basis of experimental evidence relating chemical properties to electron distributions, it was suggested that in the atoms of the noble gases heavier than helium, the electrons are arranged in these shells in such a way that the outermost shell always contains eight electrons, no matter how many others (in the case of radon, 78 others) are arranged within the inner shells. Britannica Stories Ringling Bros.

Folds Its Tent In a theory of chemical bonding advanced by American chemist Gilbert N. Lewis and German chemist Walther Kossel in 1916, this octet of electrons was taken to be the most stable arrangement for the outermost shell of any atom. Although only the noble-gas atoms possessed this arrangement, it was the condition toward which the atoms of all other elements tended in their chemical bonding. Certain elements satisfied this tendency by either gaining or losing electrons outright, thereby becoming ions ; other elements shared electrons, forming stable combinations linked together by covalent bonds . The proportions in which atoms of elements combined to form ionic or covalent compounds (their “ valences ”) were thus controlled by the behaviour of their outermost electrons, which—for this reason—were called valence electrons . This theory explained the chemical bonding of the reactive elements, as well as the noble gases’ relative inactivity, which came to be regarded as their chief chemical characteristic.

(See also chemical bonding: Bonds between atoms .) Shell atomic model Periodic Table of the Elements Screened from the nucleus by intervening electrons, the outer (valence) electrons of the atoms of the heavier noble gases are held less firmly and can be removed (ionized) more easily from the atoms than can the electrons of the lighter noble gases. The energy required for the removal of one electron is called the first ionization energy . In 1962, while working at the University of British Columbia , British chemist Neil Bartlett discovered that platinum hexafluoride would remove an electron from (oxidize) molecular oxygen to form the salt [O2+][PtF6−]. The first ionization energy of xenon is very close to that of oxygen; thus Bartlett thought that a salt of xenon might be formed similarly. In the same year, Bartlett established that it is indeed possible to remove electrons from xenon by chemical means. He showed that the interaction of PtF6 vapour in the presence of xenon gas at room temperature produced a yellow-orange solid compound then formulated as [Xe+][PtF6−].

(This compound is now known to be a mixture of [XeF+][PtF6−], [XeF+] [Pt2F11−], and PtF5.) Shortly after the initial report of this discovery, two other teams of chemists independently prepared and subsequently reported fluorides of xenon—namely, XeF2 and XeF4. These achievements were soon followed by the preparation of other xenon compounds and of the fluorides of radon (1962) and krypton (1963). Connect with Britannica Facebook Twitter YouTube Instagram Pinterest In 2006, scientists at the Joint Institute for Nuclear Research in Dubna , Russia , announced that oganesson , the next noble gas, had been made in 2002 and 2005 in a cyclotron . (Most elements with atomic numbers greater than 92—i.e., the transuranium elements —have to be made in particle accelerators.) No physical or chemical properties of oganesson can be directly determined since only a few atoms of oganesson have been produced.

General properties of the group Each noble-gas element is situated in the periodic table between an element of the most electronegative group, the halogen elements (Group 17, the atoms of which add electrons to achieve the octet and thereby become negative ions ), and an element of the most electropositive group, the alkali metals (Group 1, the atoms of which lose electrons to become positive ions). Several important uses of the noble gases depend on their reluctance to react chemically. Their indifference toward oxygen , for example, confers utter nonflammability upon the noble gases. Although helium is not quite as buoyant as hydrogen , its incombustibility makes it a safer lifting gas for lighter-than-air craft. The noble gases—most often helium and argon , the least expensive—are used to provide chemically unreactive environments for such operations as cutting, welding , and refining of metals such as aluminum (atmospheric oxygen and, in some cases, nitrogen or carbon dioxide would react with the hot metal).

The helium-filled balloon Bubble, manned by a scientist … James Aldred/Nature Picture Library Editor Picks: Exploring 10 Types of Basketball Movies The noble gases absorb and emit electromagnetic radiation in a much less complex way than do other substances. This behaviour is used in discharge lamps and fluorescent lighting devices: if any noble gas is confined at low pressure in a glass tube and an electrical discharge is passed through it, the gas will glow. Neon produces the familiar orange-red colour of advertising signs; xenon emits a beautiful blue colour. Neon signs along Nanking Road, Shanghai. Paul Souders/Corbis Noble gases have uses that are derived from their other chemical properties. The very low boiling points and melting points of the noble gases make them useful in the study of matter at extremely low temperatures . The low solubility of helium in fluids leads to its admixture with oxygen for breathing by deep-sea divers : because helium does not dissolve in the blood , it does not form bubbles upon decompression (as nitrogen does, leading to the condition known as decompression sickness , or the bends ). Xenon has been used as an anesthetic ; although it is costly, it is nonflammable and readily eliminated from the body.

Radon is highly radioactive ; its only uses have been those that exploit this property (e.g., radiation therapy ). (Oganesson is also radioactive, but, since only a few atoms of this element have thus far been observed, its physical and chemical properties cannot be documented.) Only krypton , xenon, and radon are known to form stable compounds. The compounds of these noble gases are powerful oxidizing agents (substances that tend to remove electrons from others) and have potential value as reagents in the synthesis of other chemical compounds . noble gases - Student Encyclopedia (Ages 11 and up) Six elemental gases are composed of such exceptionally stable atoms that they almost never react with other elements. They are the gases that make up Group 0 (the rightmost column) of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). When they were first discovered, these gases were thought to be exceedingly rare and completely inactive; thus they were named the rare gases, inert gases, or noble gases (the term noble, in chemistry and alchemy, had long signified a lack of chemical reactivity).

Article Contributors List of Noble Gases | eHow List of Noble Gases neon sign image by pearlguy from Fotolia.com The six noble gases are all found in group 18 of the periodic table. Noble gases are different from other elements because they have a full set of electrons in their outer shell. Most gases have too few or too many. This complete electron shell makes noble gases very stable, a fact that once saw them referred to as "inert gases." However, some of the noble gases are now known to take part in chemical reactions. Helium Helium has an atomic number of 2 and is represented by the symbol He. The gas was discovered in 1895, but, according to the BBC website, its existence had been previously proposed by Pierre Jules Cesar and Sir Joseph Norman Lockyer. The two men that named the gas "helium" after the Greek word for sun. Helium is often used in balloons due to its lighter than air properties. It is also used in deep sea diving equipment to dilute a diver's oxygen supply. Neon Neon has an atomic number of 10 and the symbol Ne.

It was discovered in 1898 by two British chemists, William Ramsay and Morris W. Travers, and named after the Greek word for new, "neos." Neon is often used in lighting and fluorescent signs. The gas itself is colorless but glows in an electric discharge. Argon Argon has an atomic number of 18 and the symbol Ar. It was isolated in 1894 by Lord Rayleigh and William Ramsay, becoming the first of the noble gases to be discovered. The stable nature of the gas earned it the name "argon," the Greek word for inert. According to the Royal Society of Chemistry website, "Argon is widely used to provide an inert atmosphere for high-temperature metallurgical processes." Like neon, it is also used in lighting. Krypton Krypton is represented by the symbol Kr and has an atomic number of 36. Krypton was discovered in 1898 by William Ramsay and Morris W. Travers, just a few weeks before they discovered neon. It was named after the Greek word "kryptos," meaning hidden. The gas is used in fluorescent lighting and in various types of photographic flash bulbs.

Xenon Xenon has an atomic number of 54 and the symbol Xe. It was discovered by Ramsey and Travers in 1898, shortly after their discovery of neon and krypton, and named after the Greek word for stranger. Xenon is found naturally in the atmosphere, but only in minute quantities. According to the PeriodicTable.org website, xenon is used in photographic flashes, general anesthetic and stroboscopic, bactericidal, and laser-pumping lamps. Radon Radon, the last noble gas to be isolated, has an atomic number of 86 and the symbol Rn. It was initially observed in the 1890s before being isolated by Friedrich Ernst Dorn in 1900. It was properly classified in 1908 by William Ramsay. Radon is colorless, odorless, tasteless and, unlike the other noble gases, radioactive. It occurs naturally from decaying radium and is considered hazardous due to its radioactivity. It is used in radiotherapy for the treatment of cancer.

Group 0/18 NOBLE GASES physical properties uses helium neon argon krpton xenon radon melting points boiling points atomic radii density inertness explained gcse chemistry KS4 science igcse O level revision notes The Group 0 NOBLE GASES Doc Brown's Chemistry KS4 Science GCSE/IGCSE/O Level Chemistry Revision Notes The GROUP 0 (8/18) Noble Gases of the Periodic Table The Group 0 elements, the NOBLE GASES consist of helium, neon, argon, krypton, xenon and radioactive radon. The chemical inertness of the noble gases is explained. The physical properties of the noble gases are described and the group trends of noble gases in terms of melting points, boiling points, density, chemical reactivity and atomic radii. The 'few' chemical properties of some noble gases e.g. xenon are mentioned. The uses of noble gases are also described and explained. These revision notes on noble gases should prove useful for the new AQA, Edexcel and OCR GCSE (9ï¿½1) chemistry science courses.

See also Advanced A Level Chemistry Notes on the Group 0/18 Noble Gases BUT reading this page reminds you of what you theoretically leaned from GCSE/IGCSE/O Level courses on noble gases! So this page can act as a primer for the study of noble gases helium, neon, argon, krypton, xenon Where are the Group 0 Noble Gases in the Periodic Table? THINKING AHEAD: The Group 0 Noble Gases form the last vertical column on the right of the Periodic Table, where you find most of the non-metallic elements. Therefore the Noble Gas is the last element on ANY complete period. At the bottom of Group 0 is radioactive noble gas element radon (Rn) which is not shown. Group 0 elements are on the far right of the periodic table with a very stable completely filled shell of outer electrons. You would expect them to be very unreactive non-metals. Pd The "Noble Gases" are the last group in the Periodic Table i.e. they form the last elements at the end of a period, the final vertical column of elements in the periodic table. In descending order, the six noble gases are ...

helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). They were called noble 'gases' because they were so unreactive (the same reasons unreactive metals like gold are sometimes referred to as a 'noble metal'). Noble gases form the last element of a any period, with a full outer electron shell. This outer electron similarity of the noble gases makes them behave in a chemically similar way e.g. the least reactive of any elements and is a modern pre-requisite of a set of elements belonging to the same group. BUT their similarity in physical properties and the chemical reactions now known (e.g. for xenon) fits in well with Mendeleev's original conception of a group classification even though he had no idea they existed ! The noble gases are all non-metallic elements and all are colourless gases at room temperature and pressure with very low melting points and boiling points. The noble gases form 1% of air, and most of this is argon. All the noble gases, except radioactive radon, are separated by the fractional distillation of liquified air.

Helium can also be obtained from natural gas wells where it has accumulated from radioactive alpha decay (alpha particles become atoms of helium gas when they gain two electrons). alpha particle decay of the radioisotope uranium-235 Many of the unstable nuclei of heavier atoms (high proton/atomic number) decay by alpha emission. The alpha particle (helium nucleus of 2 protons + 2 neutrons) grabs 2 electrons to form a stable atom of helium gas. The electronic structure of the noble gases is the basis for explaining why they are so unreactive. The noble gases are very unreactive elements because the highest occupied electron level is complete, meaning they have a full shell of outer electrons! ( see diagrams below ). Helium has a full outer shell of 2 electrons, and the rest of the noble gases - neon, argon, xenon etc. also have a full outer shell of 8 electrons, giving them great electronic stability and chemical stability - very unreactive. The group 0 noble gases are the least reactive elements in the whole of the periodic table. They have no great 'wish' electronically to share electrons to form a covalent bond or to lose or gain electrons to form an ionic bond.

In other words, they are electronically very stable. They are sometimes referred to as inert gases, because of their lack of chemical reactivity. In fact their lack of reactivity was one reason why they were some of the last naturally occurring elements of the periodic table to be discovered. They were discovered because the density of chemically made nitrogen was different from the nitrogen obtained from air after removal of oxygen. Therefore it was reasoned that there must be some 'unknown' gases in air. With improved technology in the early 20th century, careful low temperature fractional distillation of liquified air revealed fractions containing noble gases, and this is how they are usually obtained in industry. The noble gases exist as single atoms, that is they are 'monatomic molecules' He Ne Ar etc. (NOT diatomic molecules as with many other gases like oxygen O2 and nitrogen N2 - reasons given above). This is because of their electronic stability - see point above and diagrams below . The very inertness of the noble gases and their non-flammability, are important features of their practical uses . Important group 0 noble gas trends to know down the group with increase in atomic number and relative atomic mass... ...

the melting point and boiling point of noble gases steadily increase down the group ( see data ) because the weak intermolecular forces increase with the size of the atom. This is because of the increase in the number of electrons, due to an extra electron shell from one noble gas down to the next one down the group to noble gas on the next period. This trend produces an increasingly larger atom with more, which results in an increase in the weak electrical attractive forces between the noble gas atoms (increasing intermolecular forces/intermolecular bonding). Generally speaking, these weak attractive electrical forces, the intermolecular forces (NOT chemical bonds) increase with increasing numbers of electrons in the molecule. So, because the strength of the intermolecular forces or intermolecular bonding forces between the atoms increases, so more energy (higher kinetic energy, higher temperature) is needed to boil the condensed Noble Gas and overcome these attractive forces. ... the density of noble gases steadily increases down the group ( see data ) ...

down the group, theoretically, the monatomic noble gases are more likely to react and form a compound with very reactive elements like fluorine, this is because the outer electrons are increasingly less strongly held giving a greater chance of electron sharing in forming a covalent bond with other very reactive non-metals like fluorine, chlorine and oxygen e.g. Stable compounds of xenon, like xenon tetrafluoride, are now known and synthesised BUT not before 1961! The most reactive Noble Gas would be radon BUT this is a highly dangerous radioactive gas! Some VERY unstable compounds have been made from argon and krypton. The reason for the lack of reactivity by noble gases is further explained in the box below. The atomic radii of group 0 noble gases increase down the group. ************************* Note: For atomic radii: 1nm = 10ï¿½9m, 1pm = 10ï¿½12m, nm x 1000 = pm, nm = pm/1000 Atomic radii always increase down a group with increase in atomic number because extra electron shells are successively added.

Uses of the Group 0/8 Noble Gases The noble gases are non-flammable and chemically very unreactive and this chemical inertness is an important characteristic when understanding the uses and applications of noble gases and sometimes the low density is important too. Uses of He helium The noble gas helium gas is much less dense than air (lighter) and is used in party balloons and 'airships' because it 'floats' in air! Thanks Niamh, (aged 31/2 at the time), for putting up with Granddad's camera work! Another advantage is that because of its inertness, helium doesn't burn in air UNLIKE hydrogen which used to be used in large balloons with 'flammable' consequences e.g. like the R101 airship disaster! Helium is also used in gas mixtures for deep-sea divers respiration. Liquid helium is used to achieve very low temperature in cryogenics technology. Uses of Ne neon just like this website! The noble gas neon gives out 'white light' when high voltage electricity is passed through it, so neon is used in glowing 'neon' advertising signs and fluorescent lights.

Uses of Ar argon The noble gas argon, like all the Noble Gases is chemically inert. It used in filament bulbs because the metal filament will not burn in argon and it reduces evaporation of the metal filament. Argon is also used to produce an inert atmosphere in high temperature metallurgical processes, eg in welding where it reduces brittle oxide formation reducing the weld quality. Argon bubbles are used to stir mixtures in steel production. Argon is the cheapest noble gas to produce, it has the biggest % of any noble gas in air. Uses of Kr krypton The noble gas krypton is not used by superman! BUT krypton is used in fluorescent bulbs, flash bulbs and laser beams. Uses of Xe xenon The noble gas xenon is good for winning scrabble games! AND xenon also used in fluorescent bulbs, flash bulbs and lasers! GCE AS/A2/IB Advanced Level Chemistry Notes on the Group 0/18 Noble Gases BUT reading this page reminds you of what you theoretically leaned from GCSE/IGCSE/O Level courses on noble gases!

So this page can act as a primer for the study of noble gases helium, neon, argon, krypton, xenon KS4 Science Group 0 Noble Gases GCSE chemistry guide notes on Group 0 Noble Gases for schools colleges academies science course tutors images pictures diagrams of apparatus for Group 0 Noble Gases investigations word balanced symbol equations of Group 0 Noble Gases science chemistry revision notes on Group 0 Noble Gases revising the chemistry of Group 0 Noble Gases help in chemical understanding of Group 0 Noble Gases description of Group 0 Noble Gases experiments for chemistry courses university courses in chemistry careers in chemistry jobs in the chemical industry laboratory assistant apprenticeships in chemistry technical internship in chemistry IGCSE chemistry Group 0 Noble Gases Group 0 Noble Gases USA US grade 8 grade 9 grade10 Group 0 Noble Gas chemistry IGCSE revision notes GCSE uses helium neon argon krypton noble gases KS4 Science revision notes on GCSE uses helium neon argon krypton noble gases GCSE guide notes on GCSE uses helium neon argon krypton noble gases for schools colleges academies science course tutors images pictures diagrams for GCSE uses helium neon argon krypton noble gases science revision notes on GC

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chemistry topic, formula, compound, reaction, anything of chemical interest! For latest updates see Actinides Series The Actinides series consist of the elements in the f-block in the seventh period of the periodic table. All the elements of Actinides series are radioactive and most are synthetic, that is, human-made. All have a silvery or silvery-white luster in metallic form. Periodic Table Trends When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. Some of these properties include atomic radius, electronegativity, ionization energy and metallic characteristics. Factors affecting these properties include the number of protons in the nucleus, the distance from the nucleus and amount of shielding inner electrons provide to the valence electrons. Atomic radius The atomic radius is a somewhat imprecise measure that can refer to the mean distance from the center of the nucleus to the boundary of the surrounding electron cloud. We can determine the radius by dividing the distance between two bonded atoms in half. Depending upon the type of bond we can obtain very different values. If the bond is covalent it is called a covalent radius. If the bond is ionic it is called an ionic radius.

The Atomic radius tend to decrease when moving across a period from left to right. As we move across a period electrons are added to the same energy level and protons are added to the nucleus; increasing the effective nuclear charge and pulling the electrons closer to the nucleus. The Atomic radius tend to increase when moving down a group from top to bottom. As we go down a group additional energy levels are added; and each subsequent energy level is further from the nucleus. Electronegativity Electronegativity is the tendency of an atom to attract electrons. It cannot be measured directly and needs to be computed from other atomic properties. The Pauling scale is a dimensionless quantity developed by Linus Pauling used to describe the electronegativity of an atom. The two key factors in determining electronegativity are its atomic number and radius. Fluorine has the highest electronegativity and francium the lowest. If the electronegativity difference between two atoms is very large, then the bond type tends to be more ionic, if the difference in electronegativity is small then it is a nonpolar covalent bond.

Ionization energy The first ionization energy is the energy it takes to remove an electron from a neutral atom in gaseous phase. In general, the 1st ionzation energy increases as we go across a period; as the electrons are held closer to the nucleus with the increasing effective nuclear charge. In general, the 1st ionization energy decreases as we go down a group; as the electrons are further from the nucleus with each increasing energy level. The noble gases possess very high ionization energies because their full valence shell makes them highly stable. In general, the (n+1)th ionization energy is larger than the nth ionization energy. Metal Characteristics Metals are usually shiny, malleable, hard and are good conductors of electricity and heat. Metals have low ionization energy and low electronegativity which allows them to conduct electricity as electrons can flow through them easily. Metal characteristics tend to increase when moving from the top-right to bottom-left of the periodic table. The most nonmetallic elements(oxygen, fluorine, chlorine) occur at the top right of the Periodic Table. Periodic Table blocks The periodic table can be divided up into several blocks based on their highest energy electron orbital type.

There are 4 types of electron orbitals; "s" which can hold 2 electrons and is sperical in shape, "p" which can hold 6 and is shaped like a dumb-bell, "d" which can hold 10 and "f" which can hold 14. For example Helium has an electron configuration of 1s2; the "1" denotes the energy level or shell (also known as the principle quantum number "n") the "s" the type of orbital and the "2" denotes the number of electrons. The s-block consists of the groups 1 and 2 elements plus Helium. The p-block consists of the groups 13 to 18 elements but not Helium. The d-block consists of the groups 3 to 12 elements. The f-block consists of the Lanthanides and Actinides. We can also divide the table between main group and transition metals. The main group elements include groups 1 and 2 (excluding Hydrogen) on the left of the periodic table and groups 13 to 18 on the right of the table.

The transition metals are the metallic elements that serve as a bridge, or transition, between the two sides of the table. The lanthanides and the actinides at the bottom of the table are sometimes referred to as the inner transition metals.

Question: The names of five of the six elements that make up the Nobel Gases end with which two letters?
Answer: -ON